Implication of nanostructuring of bulk nanocomposite Ti9Ni7Sn8 on the optimization of high thermoelectric performance

Abstract

Abstract Nanostructuring approach on TiNiSn-based half-Heusler (HH) thermoelectric materials (TE) has been well established as the most prominent paradigm for achieving high figure of merit (ZT). Herein, we have extended this approach on our previously reported bulk nanocomposite (BNC), containing HH and Full Heusler (FH) with little traces of Ti 6 Sn 5 phase in a stoichiometric composition Ti 9 Ni 7 Sn 8 for the optimization of high thermoelectric performance. A synergistic effect of nanostructuring of Ti 9 Ni 7 Sn 8 bulk nanocomposite (BNC) on its thermoelectric properties was noticed, revealing an enhanced value of ZT ~ 0.83 at 773 K. This enhancement in ZT value is mainly ascribed to significant reduction in thermal conductivity ( κ ~ 1.0 W/mK at 773 K), through modification in grain as well as phase boundary scattering. The marginal enhancement in Seebeck coefficient observed is attributed to charge carrier filtering effect at the interface of HH/FH phases.